Airplane



B D. THOMAS.

AIRPLANE.

APPLICATION FILED DEC.4, l9l9.

Patented Aug. 30, 1921.

AT HNEY UNITED STATES PATENT OFFICE.

AIRPLAN'E.

Specication of Letters Patent.

Patented Aug. 30, 1921.

Application led December 4, 1919. Serial No. 342,316.

T 0 all whom it may concern:

Be itknown that I, BENJAMIN DOUGLAS THOMAS, a subject of Great Britain, residing at Ithaca, in the county of Tompkins and State of New York, U. S. A., have invented a certain new and useful Improvement in Airplanes, of which improvement the following is a specification.

This invention relates to airplanes, and more particularly to the trussed structure of the wings, the obj ect being to increase the factor of safety and provide an improved system of diagonal bracing, whereby the wing structure will not fail even if one of the diagonal truss members should break.

My invention comprises a double intersection system of diagonal bracing wherein the tension members extend over two panel lengths instead of one, and also having in the first panel, additional diagonal bracing members extending from the-upper portion or side of the fuselage to the top and bottom of the rst panel strut member.

In the accompanying drawing: the figure is a front elevation, in diagram, of an airplane embodying my improvement.

The figure shows the usual biplane construction comprising fuselage, 1, upper wing spars, 2, lower wing spars, 3, and vertical struts, 4, 5, and 6, connecting the upper and lower wing spars, and forming the panels of the truss at each side of the fuselage.

The frame of the body or fuselage may be attached at the bottom to the lower wingspars in the usual way, and the upper part may be rigidly connected with the upper wing spars in any suitable manner, as by means of the usual short strut, 7. The first panel thus extends from the fuselage at each side out to the first strut, 4, while the second panel is between struts, 4 and 5, and the third panel between struts, 5 and 6, and so on for any number of struts that may be employed.

According to the prior construction, the diagonal bracing for each panel comprises a single pair of tension wires connecting the diagonally opposite corners of the panel, but with such form of diagonal bracing it will be evident that if one of said diagonal wires, say in the first panel, should fail, the

wing structure would be very liable to break off at the first panel point or strut. .According to my improvement, however, the diagonal tension -wires extend over the length of two panels of the truss and conneet the panel point or strut at one of the wing spars with the alternate or second panel point at theother wing spar, thus making a double intersection diagonal braclng. As shown on the drawing, this includes the diagonal lift wire, 8, connecting the lower Ypart of the fuselage at the lower wing spar with the panel point' at the top of the second strut, 5, and the lift wire, 9, connecting the bottom of the rst panel strut, 4, with the panel point at the top of the alternate strut, 6, also the diagonal ground wire, 10, connecting the panel point at the top of short strut, 7, with the second panel point at the bottom of Strut, 5, and the landing wire, 1l, connecting the top of the first strut, 4, with the alternate panel point at the bottom of strut, 6. There are also the diagonal lift wires, 12, connecting the upper portion of the fuselage with the panel point at the top of the strut, 4, and landing wires, 13, connecting the upper portion of the fuselage with the bottom of the strut, 4.

Of these two sets of diagonal bracing, the lift wires are adapted to take the stresses during flying, while the ground or landing wires are subject to stress when under static conditions, and during landing. The system of bracing is the'same at each side of the center of the fuselage.

With my improved double system of diagonal bracing, the truss construction will have the advantages of greater strength and safety, since it will be apparent that if the lift wire, 12, should fail, the load on the upper wing for the first' two panels, and the corresponding pressure on the lower` wing, acting through strut, 4, would then be carried by the lift wire, 8, assisted by lift wire, 9. These wires are sufficiently strong so that there would still be a factor of safety which would keep the wing structure from failing. Also, in the event that the lift wire, 8, should fail, that portion of the load in the second and third panels taken by wire, 8, would then be bornel by wires 12 and 9, and the stresses fon the wing spars would also be increased, but there would still be a sufficient factor of safety to prevent the wing structure from failing. The same advantage of increased safety also applies to the double system of landing or ground wires, although these are not so important as the lift wires, which are under stress during flight.

It will also be apparent that with my improved double system, the stresses produced in the wing spars, and in the interplane struts, 4 and 5, are not as great under the normal conditions of ying as with the former construction having the single diagonal system for each panel of the truss. It will also be seen that my improvement will not add materially to the weight nor to the head resistance of the airplane.

. tension members connecting the upper portion of the fuselage with the top of the first panel strut, and the lower portion of the fuselage with the top of the second panel strut.

2. In an airplane, the combination with a fuselage, upper and lower wing spars, and struts joining the upper and lower spars and forming the panels of the truss, of a short strut connecting the upperI portion of the fuselage with the upper wing spar, and diagonal tension members connecting the u per part of the fuselage with the bottom of tllaj fuselage, upper and lower wing spars, and

struts joining the upper and lower spars and forming the panels of the truss, of a short strut connecting the upper portion of the fuselage with the upper wing spar, and diagonal tension members connecting the top of said strut with the bottom of the second panel strut, and the bottom of said strut with both the top and the bottom of the first panel strut.

4. In an airplane, the combination with a fuselage, upper and lower wing spars, and struts joining the upper and lower spars and forming the panels of the truss, of a short strut connecting the upper part of fuselage with the upper wing spar, and di.- agonal tension members connecting the top, of said short strut with the bottom of the second panel strut, and the bottom of the j BENJAMIN DOUGLAS THOMAS. 

